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43 lines
1.5 KiB
Python
43 lines
1.5 KiB
Python
from django.db.models.signals import pre_save
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from django.dispatch import receiver
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from rest_framework.exceptions import ValidationError
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from blockchain.models import Transaction
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from utils.blockchain import get_balance, transfer_rubbles
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@receiver(pre_save, sender=Transaction)
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def validate_create_transaction(sender, instance: Transaction, **kwargs):
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# validate transaction
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if instance.user_from == instance.user_to:
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raise ValidationError("Cannot transfer to yourself")
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if instance.amount == 0:
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raise ValidationError("Cannot transfer 0 money")
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# Potential Race condition, use transaction with atomics in prod
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user_from_money = int(get_balance(instance.user_from.wallet_public_key).coins)
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if instance.user_from.money != user_from_money:
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instance.user_from.money = user_from_money
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instance.user_from.save(update_fields=["money"])
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if user_from_money - instance.amount < 0:
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raise ValidationError(
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f"{instance.user_from.username} doesn't have enough money"
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)
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try:
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transaction = transfer_rubbles(
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instance.user_from.wallet_private_key,
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instance.user_to.wallet_public_key,
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amount=instance.amount,
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)
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except AttributeError:
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raise ValidationError("Transaction unsuccessful")
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instance.user_from.money -= instance.amount
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instance.user_from.save(update_fields=["money"])
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instance.user_to.money += instance.amount
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instance.user_to.save(update_fields=["money"])
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instance.hash = transaction.transaction_hash
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